A typical process in the manufacturing of a liquid crystal display includes the following steps: cleaning a substrate; forming a photoresist; exposing; and developing. An apparatus for processing the substrate during these steps typically uses a treating liquid. In particular, a cleaning device and a developing device of the apparatus use the treating liquid. With large-sized liquid crystal panels now commonplace, the amount of treating liquid needed for processing the corresponding substrates can be considerable.
Referring to FIG. 3, a typical apparatus 10 for processing substrates includes a substrate cleaning device 70 and a treating liquid circulation device 165. The treating liquid circulation device 165 has a drainpipe 140, a treating liquid holding unit 168, a through flowline 166, and a pair of treating liquid providing devices 151, 152. The drainpipe 140 is connected with the substrate cleaning device 70 and the treating liquid holding unit 168. The drainpipe 140 can convey treating liquid that has been used in the substrate cleaning device 70 to the treating liquid holding unit 168. The through flowline 166 is connected with the treating liquid holding unit 168 and with the treating liquid providing devices 151, 152. The through flowline 166 can convey the treating liquid that is held in the treating liquid holding unit 168 to the treating liquid providing devices 151, 152, whereupon such treating liquid can be conveyed to the substrate cleaning device 70 for reuse. The treating liquid circulation device 165 has a mirage trap 142, which is set between the drainpipe 140 and the treating liquid holding unit 168. The mirage trap 142 can remove air bubbles from the treating liquid. The treating liquid circulation device 165 also has a filtering device 167, which is set between the mirage trap 142 and the treating liquid holding unit 168. The filtering device 167 can filter impurities from the treating liquid.
In summary, the apparatus 10 comprises the substrate cleaning device 70, which makes use of recycled treating liquid to clean substrates. This is accomplished by directing used treating liquid form the substrate cleaning device 70 through the treating liquid circulation device 165.
However, in the overall process of manufacturing the liquid crystal panel, the developing process as well as the substrate cleaning process needs treating liquid. The apparatus 10 only recycles treating liquid used in the cleaning substrate process. Treating liquid used in the developing process is discarded after use.
Further, the substrate cleaning process and the developing process have different demands for cleanliness of the treating liquid. Generally, the level of cleanliness required in the developing process is lower than that in the substrate cleaning process. Thus when new treating liquid is used in the developing process and then discarded, this is considered by many to be wastage of treating liquid.
What is needed, therefore, is a new apparatus for processing substrates which overcomes the above-described problems. What is also needed is a new method involving such apparatus.